Surface fasteners have been widely used in various applications as a fastening means which is easy to engage and disengage and can be repeatedly used. Cloth hook surface fasteners and cloth loop surface fasteners, which are composed of a base fabric formed from woven fibers or knitted fibers and hook engaging elements or loop engaging elements projecting from the surface of the base fabric, have been widely used in articles for daily use or business use such as clothes, briefcases and bags.
The cloth hook surface fastener for daily use is sometimes required to withstand the ironing temperature, and the cloth hook surface fastener for business use is sometimes required to have a heat resistance enough to withstand the high-temperature environment. Since the ironing temperature is about 200° C. at highest, a known hook surface fastener made of polyester fibers manages to withstand the ironing temperature. However, since the engaging elements gradually lose their shapes and engaging performance after repeated ironing, a further improved heat resistance is still required. In addition, the hook surface fastener is sometimes used in an environment of 200° C. or higher for a long period of time in the business application. Therefore, a hook surface fastener which maintains the engaging performance even under a high-temperature environment is keenly required. The known hook surface fastener made of polyester fibers cannot meet the requirements in the business application. Further, a still higher heat resistance and flame resistance come to be required in some applications such as fireman uniform.
In addition, the hook engaging elements are pulled during the repeated engagement-disengagement operations of the hook surface fastener and the loop surface fastener and the hook engaging elements are pulled out of the base fabric of the fastener in some cases. To avoid this problem, the hook engaging elements are generally anchored to the base fabric by coating an adhesive resin on the back surface of the base fabric. However, the adhesive resin coat on the back surface of the base fabric reduces the heat resistance and the flame resistance of the surface fastener, and in many cases, deteriorates the flexibility of the surface fastener.
It has been reported that a surface fastener made of filaments having a melting point of 250° C. or higher and binder fibers for fusion-bonding the filaments has an improved heat resistance (Patent Document 1). As the high-melting point filaments, fibers of a polyester-based polymer and fibers of other polymers such as a liquid crystal polymer, polybenzimidazole and polyphenylene sulfide (PPS) are described (paragraph 0073). However, only a surface fastener made of polyester fibers is actually disclosed in the working examples of Patent Document 1. While a surface fastener made of other types of fibers, particularly, made of PPS fibers is noted in the broad teachings, Patent Document 1 provides no further teaching and addresses nothing about such a surface fastener.
Patent Document 2 discloses PPS monofilaments which exhibit an extremely high heat stability such as a high retention of tensile strength even after a long use at high temperatures. It is taught that the PPS monofilaments are produced by spinning, drawing and heat-treating at about 120 to 280° C. under about 0.8 to 1.0 times of tension. However, the heat treatment actually made in the working examples is performed only at 180° C. after spinning and drawing (paragraph 0043). In the examples of Patent Document 2, the variation of fiber diameter after the heat treatment at 250° C. for 400 h is described. However, the long-time heat treatment is made for only evaluating the variation of fiber properties and clearly distinguished from the heat treatment employed in the present invention for improving the engaging performance of the hook engaging elements.    Patent Document 1: JP 8-280418A (paragraph 0073)    Patent Document 2: JP 2001-123324A (paragraph 0043)